Circuit interrupter



Sept. 10, 1940. w. MLEEDS ET AL CIRCUIT INTERRUPTER Filed May 25, 195' 7 Sheets-Sheet 1 INVENTORS W/nfhrop M. Leeds & Erm/o Orfensi BYK/ f a ATTORN;

WITNESSES; f F Wall 4!.

Sept. 10,1940. w. M. LEEDS ET AL CIRCUIT INTERRUPTEH Filed May 25. 195' 7 Sheets-Sheet 3 INVENTORS l/V/n fhrop M Leeds 1? Erin/'0 Orfems/ 4 BY 1/ ATTORNE p 10, 1940. w. M. LEEDS ET AL 2,21 ,620

CIRCUIT INTERRUPTER Win fhrap Mieeds A? Wad M qfnni a Zfens/ 5 ATTORNEY;

w. M. LEEDS ET AL CIRCUIT INTERRUPTER Sept. 10, 1940.

7 Sheets-Sheet 6 Filed May 25, 195' Enn/o Orfens/ Y7 ATTOR Y iii) Patented Sept. 10, 1940 UNITED STATES PATENT OFFICE CIRCUIT INTERRUPTER Application May 25, 1937, Serial No. 144,626

20 Claims.

This invention relates to circuit interrupters, and more particularly to circuit interrupters of the liquid immersed type.

In United States Patent No. 1,899,605, issued February 28, 1933, to B. P. Baker and E. G. Kees, and assigned to the assignee of this application, is described a circuit interrupter of the liquid immersed type having an arc extinguishing structure consisting of a stack of slotted plates of insulating material interspersed with slotted plates of magnetic material. The slots in the respective plates are open at one end and aligned so as to form a passage or groove in which an arc may be drawn. The are is drawn within the passage adjacent the open side thereof and caused to be moved inwardly by the magnetic reaction resulting from the distorted magnetic field up by the slotted plates of magnetic material.

The action of the arc during its movement through the arc extinguishing liquid produces a gas composed largely of relatively cool unionized particles, which is caused to flow through the arc stream and escape along the open side of the are In flowing through the arc stream, the un-ionized particles are turbulently intermixed with the ionized particles which sustain the are. This intermixing causes the arc stream to become less and less conducting so that when current zero is reached in the current wave, deionization has progressed sufliciently to prevent the are from restriking as the voltage builds up in opposite direction following cur-- rent Zero.

Arc interruption has been materially improved by substantially completely enclcsinc the arc passage, as shown and described in United States Patent No. 1391301, issued February 19, 1935, to W. M. Leeds and assigned to the assignee of this application. The improvement is eifeeted by the provision of vent openings so positioned with spect to the arc passage that the arc subjected to the combined efiect of a longitudinal and a cross blast of gas.

Although the operation of the arc extinguisher of the shown in the aforesaid Patent No. 1,391,901 represents a material improvement over the operation. of devices prior thereto, we have disco. ed. that further improvements may be umde whereby hetter operation is obtained over reader ran e of current values. Particularly at l at current values the arc does not readily transfer from the main contact to the arcing horn on account of the relatively weak magnetic pull. set up by the slotted plates of magnetic material interspersed between the plates of insulating material forming the side walls of the arc passage. The are, therefore, remains adjacent the are drawing contacts Within a low pressure gas-fll1ed pocket formed by the high speed movement of the movable contact to the open position. This pocket contains largely ionized particles thereby making arc extinction more diflicult. We have found that this difficulty can be overcome by injecting additional arc extinguishing liquid under pressure into the arc passage and through the arc stream, which greatly increases the ratio of un-ionized to ionized particles and thus hastens arc extinction.

The main object of our invention, therefore, is to improve the operation of circuit interrupters of the type above described.

A further object of our invention is to provide a circuit interrupter having improved performance over a broad range of current values.

A more specific object of our invention is to provide means in a circuit in errupter of the liquid immersed type for causing a more rapid deionization of the arc stream.

Other objects relate to details of the structural arran ement peculiarly adapted for the accomplishment of the above-named objects and which will appear more fully in the following description and the accompanying drawings, in which:

Figure 1 is a side elevation partially in section showing a circuit interrupter embodying our invention;

7*}. 2 is a sectional view taken along line cf Fig. 4, showing one of the arc extinguishing units of our invention;

Fi 3 is a sectional view of one of the are extin dishing units taken along the line III-III of Fig. 4;

Fig. i an end elevation view of one of the arc extinguishing units forming part of the circuit interrupter of our invention; v

Fi s. 5 to 16, inclusive, show details of the respective plate elements which constitute each of the arc extinguishing units;

17 is an end elevation view showing the aoi-ua mechanism for the are extinguishing structures of our invention;

18 is a side elevation View of the actuating mechanism shown in Fig. 17;

19 is a sectional view of the actuating r tar nism in the closed circuit position, to the left of section line XIXX[X of Fig. 1'7 and viewed from the line XXI-XXI of Fig. 17;

Fig. 22 shows the mechanism of Fig. 21 in the open circuit position;

Fig. 23 is a side elevation view showing only the equalizing linkage in the closed circuit position of the mechanism shown in Figs. 17 and 18; and

Fig. 24 is a side elevation view of the equalizing linkage of Fig. 28 in the open circuit position.

Referring to Fig. 1 of the drawings, the reference numeral I designates a base, in this instance serving as the sole support for the circuit breaker structure and in which a suitable operating mechanism (not shown), may be housed. Upon the base is mounted an insulator 3, which in turn supports a tubular housing generally indicated at 5, in which the circuit interrupter proper is contained.

The housing 5 comprises a central housing member 1, preferably of metal, in which an ac tuating mechanism, generally indicated at 9, is positioned. The housing 7 has two opposed circular end plates i, to each of which an arc extinguishing unit, only one of which is generally indicated at l3, is secured. Each of the are extinguishing units I3 is surrounded by a tubular pressure or strain member l5, of strong insulating material. The strain members 5 may be secured to the end plates H by means of flanges ll secured to one end of the members l5, and in turn bolted to the plate, as shown.

The outer end of each cylindrical strain member |5 may be closed by a plate |9 secured as by bolts 2|, to a flange 23, secured to the outer end of the cylindrical strain members. A weather-proof shield 25 of porcelain or other suitable material, is disposed about each cylindrical strain member l5 and may be supported at one end from an end plate I, and at the other end by a resilient metallic expansion member 27, which member in turn may be bolted to the plate 5 9, as shown. Thus, the strain members I5, acting through their respective expansion members 21, maintain the weather-proof shields 25 in position solely by subjecting the shields to compression.

Each of the arc extinguishing units !3, as more clearly shown in Figs. 2 to 4, comprises a plurality of plates of insulating material. The individual plates which comprise the stack are shown in detail in Figs. 5 to 16, inclusive. The righthand plate 3|, as viewed in Figs. 2 and 3, is shown in Figs. 15 and 16. It is preferably constructed of insulating material having considerable thickness and is provided withfour apertures 33, screw-threaded for the reception of a tubular guide member 35, as more clearly shown in Fig. 3.

Adjacent the plate 3| is positioned a pair of plates 32 shaped as shown in Figs. 13 and 14, and also having apertures 33 extending therethrough and disposed so as to coincide with the apertures 33 in the plate 3|, thereby permitting the assembly of these plates over the four guide tubes 35. Adjacent the plates 3? is a plate 39 having a configuration as shown in Figs. 7 and 8. The plate 39 and all succeeding plates are provided with the four apertures 33 for assembly upon the guide tubes 35.

Adjacent the plate 39 is a compound plate 4| as shown in Figs. 9 and 10, which comprises an outer portion 43 of insulating material and a U-shaped insert 45 of magnetic material. The

portions 43 and 45 are of the same thickness and are adapted to be disposed between two plates 39. The purpose of the magnetic insert 45 will be fully explained hereinafter.

Adjacent the plate 4| is positioned a second plate 39. The remaining plates comprise alternately a series of two plates designated 31 and a series of three plates designated 39, 4|, 39, with the exception of the last six plates of insulating material. A pair of plates 41, as shown in Figs. 11 and 12, are similar to the plates 3? shown in Figs. 13 and 14, with the exception that the former plates have a recessed notch 49 in one end thereof to form a vent passage, the purpose of which will be more fully described hereinafter.

The next group of three plates in sequence is designated 5|, 4|, 5|, the plates 55 being similar to plates 39 shown in Figs. '7 and 8, with the ex ception that they have an open slot shown at 53 in Fig. 2. The intermediate plate 4|, however, in this last-named series of three plates, is the same as previously described. The outermost plate of insulating material designated at 55 is substantially of the same thickness as plate 3| and is shown in detail in Figs. 5 and 6. In addition to the apertures 33, the plate 55 is provided with countersunk recesses 57 for the reception of a spanner nut 59, which nut is adapted to be threaded upon each of the guide tubes 35. It is thus seen that the four guide tubes 35, with their respective nuts 59, serve to hold the entire stack of insulating plates in the assembled position.

It will be observed that the plates 39 and 4| are provided with an elongated slot 6|, one end of which is somewhat enlarged for a purpose which will be hereinafter described. The plates 31 and 47 are provided with a slot 63 similar in general outline to the slots 6| but which has, in addition, recesses or indentations 55 extending on opposite sides thereof. It will be observed that the stack of plates arranged as shown in Figs. 2 and 3 provide for a slot-like arc passage 62, the cross-section of which is determined by the slot 6| which provides for an enlarged portion 5i and a restricted portion 69. The outermost plate 55 of insulating material also has a slot therethrough designated at H, which slot is somewhat wider than the slot 6| in the plates 39 and 4|. A portion of the opposed side walls of the slot "H is bevelled outwardly as shown at 13, the purpose of which will appear more fully hereinafter.

Adjacent the plate 55 is a metal head plate 15, which in this instance, may be secured to the stack of insulating plates by means of four tie rods IT, as more specifically shown in Fig. 3. The tie rods ll are preferably of insulating material, one end of which is provided with a metallic flanged head portion 19 and the other end with a threaded metallic portion 8!. The tie rods T! are adapted to pass through the end plates H of the housing '1 and through the tubular guide rods 35, thereby securely fastening the head plate '15 to the unit i3, which unit in turn is securely fastened to the end plates H. The head plate :"5 is provided with a rectangular aperture 85 for the reception of a yieldingly mounted stationary contact 87.

The contact 81 is carried by a cylindrical body portion 99, the left-hand end or" which has a reduced guide portion 9|. The guide portion 9| is adapted to pass through a bracket member 93 mounted transversely of the head plate 15 upon two spaced bolts 95 having one end screwthreaded into the head plate 15. A spring 91 encircling the contact carrier 89 and interposed between the bracket 93 and the contact 81 biases the latter contact into the aperture 85.

Adjacent the aperture and secured to the inner side of head plate 15 is an inclined arc horn 99. The arc born 99 is adapted to project into the slot 'II of the plate 55 and is somewhat narrower than the slot. The are horn 99 is electrically connected to the contact carrier 89 by a pair of flexible shunt connections I00, each having one end connected to the contact carrier 89 and the other end connected to the head plate 15.

The fiber plate 3I, as well as the end plate II of the housing 1, is provided with a rectangular aperture IOI for the purpose of receiving a rectangular contact rod I03. The aperture IN is in axial alignment with the aperture 85 in the head plate 15, hereby permitting the contact rod I03 to be moved slidably through the plates I I and 3| into and out of engagement with the contact 81. In Fig. 2, the contact rod I03 is shown in the open circuit position. The contact 81 and the cooperating contact rod- I03 are also disposed in axial alignment with the enlarged portion 01 of the arc passage 62.

An are established between the contact 81 and the contact rod I03 as a result of movement of the latter to the open position, will be moved laterally into the restricted portion 69 of the passage 62 as a result of a magnetic reaction set up by the arc in the U-shaped inserts 45 of magnetic material forming part of the composite plates 4|. The magnetic. pull exerted by the slotted plates 45 causes the left-hand end of the arc, as viewed in Fig. 2, to transfer from the stationary contact 81 to the arc horn 99. Inasmuch as the are extinguishing unit I3 is wholly immersed in arcextinguishing liquid, the passage 62 as well as the pockets 65, will be filled with liquid and the are drawn therein will decompose portions of the liquid forming quantities of relatively cool unionized gas. This gas escapes from the arc passage 62 by way of the recessed openings 49 provided in the plates 41 and also the slot openings 53 provided in the plates 5|. It will be noted from Fig. 2 that any gas flowing towards these vent openings must necessarily pass through the arc stream and thus will be turbulently inter mixed with the arc stream, causing rapid deionization thereof.

In order to hasten the deionization action during arc extinction, we have provided means for injecting additional arc-extinguishing liquid into the arc stream in a direction which is opposed to arc movement. In order to obtain this addition a1 circulation of liquid in the arc chamber 62, we have provided the plates 3|, 31, 39, 4|, 41, 5I and 55 with circular apertures I05. The apertures I05 are positioned adjacent the ends of the slots in these plates and are adapted to receive a tubular member I01, preferably of insulating material, which may be screw-threaded at its right-hand end into the end plate 3|. The left-hand end of the tubular member I01 is provided with a slot I09 which is adapted to register with the slot H in plate 55 and the slot GI in plates 5I. The tubular member I01 serves as a cylinder wall and is adapted to receive a piston III mounted for sliding movement therein and is actuated by a connecting rod I I3.

It will appear more fully hereinafter in connection with the description of the actuating mechanism 9, that as the contact rod I03 is separated from the stationary contact 81, piston I I I is moved to the left within the cylinder I01, thereby expelling the liquid contained therein through the slotted opening I09 into the arc chamber 62. This stream of liquid flows along the arc horn 99 through the arc, thereby increasing the turbulent intermixing of arc extinguishing liquid with the arc stream which further hastens deionization and consequently, arc extinction.

The effect of injecting additional liquid into the arc passage 62 is particularly noticeable during the interruption of arcs of relatively low current magnitude. Under this condition of operation, the slotted magnetic plates 45 exert a relatively weak pull upon the arc and there is a tendency for the arc to remain in the enlarged portion 61 of the arc passage 62, and it does not readily transfer onto the arc horn 99. The efiect of the rapid separation of the contact rod I03 from the stationary contact 81 is to produce a pocket in the arc extinguishing liquid between these contacts, which rapidly fills with low pressure gas containing largely ionized particles. The injection of additional arc extinguishing liquid into the arc passage 62 by means of the piston III reduces the ionization and raises the pressure in the gas-filled pocket. The injection of additional arc extinguishing liquid under pressure also assists in expelling the gas from the passage through the vent openings 49 and 53.

The head plate 15 may also be provided with an aperture I IS in coaxial alignment with the cylindrical passage formed by the tubular member I01, into which a yieldingly mounted valve and stop member iI1 projects. The stop member H1 is biased toward the head plate 15 by a spring H9 and guided in its movement by a suitable aperture I2I in the bracket 93. The head of piston III engages and actuates the stop member I $1 to the open position when the piston reaches the end of its strokes during the opening operation of the interrupter thereby permitting further venting of the arc chamber 62 following circuit interruption. The valve and stop member II1 also permits an extinguishing liquid to flew back into the arc chamber to replenish that which was expelled during arc extinction. In the event that the pressure within the arc chamber 62 becomes excessive, we have provided additional vent means in the form of two slot-like ports I23 extending through the head plate 15, on either side of the arc horn 99. The ports I23 register with the inclined side wall portions 13 of the slot 1i positioned in the insulating plate 55. Normally, the ports I23 are covered by a valve plate I25 having a guide rod I21, secured thereto. The rod I21 is adapted for sliding movement through a sleeve I29 and aperture I3! in the bracket 93, the sleeve I29 being secured to the bracket 93 in any suitable manner.

A pair of coil springs I33 interposed between thebracket 93 and the valve plate I25 normally maintain the latter plate in the valve closing position. In order to prevent the valve plate I25 from rotating about the axis of its guide pin I21; the latter pin is slotted as shown at I35, and the bracket 93 is provided with a transverse pin I31 registering with the slot I35. It will thus be seen that by the selection of springs I33 of suitable tension and also by adjusting the distance of bracket 93 towards and from the head plate 15, the opening of valve plate I25 upon the occurrence of predetermined pressure conditions with in the arc chamber 62 may be controlled.

Although the right and left-hand arc-extinguishing units I3, as mounted in Fig. l, are identical in structure, it is believed that the description of the operating mechanism therefor will be clarified by referring to the contact rod of the right-hand unit as I03, and the piston connecting rod of that unit as H3. The right and left-hand erc-extinguishing units I3 are respectively mounted upon the end plates H of the housing 1 so that the contact rod 503 of the lefthand unit is in axial alignment with the piston connecting rod IE3 of the right-hand unit and the contact rod i633 of the right-hand unit is in axial alignment with the piston connecting rod IE3 of the lef -hand unit. The connecting rods and I3 are also provided with reduced threaded end portions Mi, which may be screwthreaded into the ends of the respective contact rods and H33, thereby joining each contact rod with a respective connecting rod of the other unit. This construction is more particularly shown in Figs. 1 and 17 to 24.

The base i may be utilized to house a suitable driving means, not shown, for actuating a rock shaft 5 35 having opposed crank arms I41 and I49 secured to one end thereof. Crank arm I49 is coupled by means of an actuating rod I5I to crank arm of the actuating mechanism generally indicated at 9 in Fig. 1.

That part of the mechanism 9 which is directly lGSpOL lble for actuating the contact rod I03 and it attached piston connecting rod H3 is shown to the right-hand side of section line XIX-XIX of Fig. 17. A side elevation view of this portion of the mechanism in the closed circuit position i shown in Fig. 19. With particular reference to this portion of the mechanism, arm E53 is part of a tubular crank member i55 having a second crank arm 251. The crank member I55 is mounted for rotative movement on pin I59, one end of which is journalled in bracket I6I secured to plate l i, and the other end of the pin is journalled in a cross rib i63 joining the respective end plates Ii of the housing 1. The crank arm I51 is coupled by a pin 65 to a pair of links I61 which in turn are coupled by pin I69 to an actuating arm ill. The lower end of the arm I1! is coupled to contact rod I03 by means of a pin I13. The upper end of arm IN is provided with a irictionally retained cross pin I15, the ends of which are slidably retained in slots I11 provided in a pair of spaced brackets I19 secured to the upper cross member E80 of the housing 1. A guide arm I8i is pivoted at its lower end by means of pin l83 to two parallel supports I85 secured to the lower cross member 586 of the housing The upper end of guide arm I8I is jointly pivoted with links I61 to the actuating arm i' I by the pin I69.

As crank arm I53 is rotated in a counter-clockwise direction. as viewed in Fig. 19, following the counter-clockwise rotation of rock arm I49, the crank I. through the coupling of links I61, will actuate arm I'll to the right. During this movement coupling pin I58 is rocked in a clock- .rection, as viewed in Fig. 19, with guide Iiii about the latters pivot I83. Straightline lotion is, however, obtained of the contact rod I03 by virtue of the fact that the upper end of actuating arm ill is slidably supported by its cross pin H5 in the slots I11. Thus it is seen that as the operating rod I5E is moved downwardly, contact rod I63 is moved to the open position, or to the right, as shown in Fig. 20, carrying with it the piston connecting rod H3.

The actuating mechanism which is directly responsible for actuating contact rod I03 of the right-hand unit and the attached piston connecting rod H3 of the left-hand unit, is shown to the left-hand side of section line 2HX-XIX of Fig. 17 as viewed at section line XXL-XXI. A side elevation view of this portion of the mechanism is shown in Fig. 21. The various members of this portion of the actuating mechanism are identical in construction to those previously described and differ only with respect to their disposition within the housing 1. It will be noted that the identical elements shown to the lefthand side of Fig. 17 and in Fig. 21 are reversed with respect to the members previously described.

With particular reference to Figs. 1, 1'7 and 21, the reference 25I designates an operating rod interconnecting crank arm I41 and crank arm 253. Arm 253 is part of a tubular crank member 255 having a second crank arm 251 secured thereto. The crank member 255 is mounted for rotative movement on pin 259, one end of which is journalled in bracket 26I secured to the left-hand plate I I, and the other end of which is journalled in a cross rib 263 joining the respective end plates of the housing 1.

The crank arm 251 is coupled by a pin 265 to a pair of links 261 which, in turn, are coupled by pin 259 to an actuating arm 21I. The upper end of arm Z'II is coupled to the contact rod I03 by means of a pin 213. The lower end of arm 21I is provided with a frictionally retained cross pin 215, the ends of which are slidably retained in slots 211 provided in a pair of spaced brackets 219 secured to the lower cross member I86 of the housing 1.

A guide arm 28I is pivoted at its upper end by means of a pin 283 to two parallel supports 285 secured to the upper cross member I60 of the housing I. The lower end of guide arm 28I is jointly pivoted with links 261 to the actuating arm 21! by the pin 269.

As crank arm 253 is rotated in a counterclockwise direction about its pivotal axis 259, as a result of upward movement of the operating rod 25I, crank arm 251, through the medium of the coupling links 261, will actuate arm 2' to the left, to the open circuit position as shown in Fig. 22, carrying with it the contact rod I03, and consequently, the attached piston connecting rod Il3. Straight-line movement of contact rod I03 and connecting rod II 3 is obtained in the manner previously described in connection with the actuating mechanism for contact rod I03 and the attached connecting rod I I3. Inasmuch as actuating rods I5I and 25I are coupled for simultaneous actuation to the respective crank arms I49 and I41, it is apparent that the contact rods and piston connecting rods of both the right and left-hand units I3 will be actuated simultaneously to either the open or closed position,

In order to further balance the reactive forces between the respective contact rods and piston connecting rods, we have provided as shown in Figures 17, 23 and 24, an interconnecting linkage which consists of a pair of levers 290 centrally pivoted about a pin 29l, the ends of which are respectively journalled in cross ribs I63 and 263. The upper ends of levers 290 are pivotally coupled to a pair of links 293 by a pin 295, and the other ends of links 293 are, in turn, jointly pivoted with actuating arm 21| to the contact rod I03 by means of the pin 213.

The lower ends of levers 290 are pivotally jointed to a pair of links 291 by means of a pin 299. The links 291 are in turn pivotally joined with the actuating arm IN to the contact rod 103 by means of the pin I13. Fig. 23 shows the equalizing linkages in the closed circuit position whereas Fig. 24 shows the linkage in the open circuit position. It will thus be seen that any reciprocating movement of one contact rod and its attached piston connecting rod will be transmitted through the linkage to the other contact rod and its attached piston connecting rod.

In order to establish a series electrical circuit through the interrupter, contact rod I03 is connected by means of a flexible conductor 3M to the contact rod I03. The electrical circuit through the left-hand are extinguishing unit [3 proceeds from the flexible conductor 3M to the movable contact rod I03 to the fixed contact 81, contact support 89, the flexible conductor 303, terminal 305, flexible conductor 301 and the external terminal 309. The terminal 309 is mounted in an end bell or cover 3| I, which end bell is supported from the end plate I9. The electrical circuit through the right-hand are extinguishing unit l3, not shown, is identical with that described in the left-hand unit.

Although we have shown and described a particular circuit interrupting structure and have shown specific detailed arrangements of the arc extinguishing units therein, it is to be understood that the same is for the purpose of illustration and that changes may be made by those skilled in the art without departing from the spirit and scope of the appended claims.

We claim as our invention:

1. In a circuit interrupter, means defining an arc passage, an arc extinguishing liquid within said passage, means for establishing an arc within said passage, means for moving said arc laterally within said passage and means for moving additional arc extinguishing liquid through said are in a direction opposite to said arc movement.

2. In a circuit interrupter, a body of are extinguishing liquid, means of insulating material defining an arc passage immersed in said liquid, said means of insulating material having pockets along the sides of said passage for trapping a considerable quantity of said liquid, separable contacts for establishing an are within said passage, means for moving said are laterally into close proximity with said entrapped liquid and means for positively moving additional liquid through said are in a direction opposite to said are movement.

3. In a circuit interrupter, a body of arc extinguishing liquid, means of insulating material defining an arc passage immersed in said liquid, said means of insulating material having pockets along the sides of said passage for trapping a considerable quantity of said liquid, separable contacts for establishing an are within said passage, means for moving said arc laterally into close proximity with said entrappedliquid, means for positively moving additional liquid through said arc in a direction opposite to said are movement, and means for causing the products of decomposition of said arc and quantities of said additional liquid to normally escape from said passage only through the arc stream.

4. In a circuit interrupter, means of insulating material defining an arc passage, said passage having an enlarged entrance portion and a constricted portion, an arc extinguishing liquid within said passage, means for establishing an arc in said entrance portion, magnetic means for moving said arc laterally into said constricted portion, and. means for positively moving an additional quantity of arc extinguishing liquid along said passage into and through the arc stream in a direction opposite to that of arc movement.

5. In a circuit interrupter, means of insulating material defining an arc passage, said passage having an enlarged entrance portion and a constricted portion, an arc extinguishing liquid within said passage, means for establishing an arc in said entrance portion, magnetic means for moving said are laterally into said constricted portion, and means for positively moving an additional quantity of arc extinguishing liquid along said passage through said are in a direction towards said entrance portion of said are passage.

6. In a circuit interrupter, means of insulating material defining an arc passage, said passage having an enlarged entrance portion and a constricted portion, an arc extinguishing liquid within said passage, means for establishing an arc in said entrance portion, magnetic means for moving said are into said constricted portion,

means for positively moving an additional quantity of arc extinguishing liquid along said passage through said are in a direction towards said entrance portion of said arc passage, and means for venting said passage adjacent said enlarged entrance portion to cause liquid and any products of decomposition of said are from said constricted portion of the arc passage to flow through the arc stream.

7. In a circuit interrupter, means of insulating material defining an arc passage, a stationary contact within said passage, a movable contact adapted to cooperates with said stationary contact for drawing an are within said passage, an arc extinguishing liquid within said passage, means for moving said are laterally within said passage, means for positively moving a quantity of arc extinguishing liquid through said are in a direction opposite-to that of arc movement, and actuating means for simultaneously operating said movable contact to establish the arc and operating said means for positively moving a quantity of arc extinguishing liquid through the arc stream.

8. In a circuit interrupter, a body of are extinguishing liquid, means of insulating material defining an arc passage immersed in said liquid, a stationary contact within said passage, a cooperating contact movable to open and closed positions, means for moving the arc established upon movement of said cooperating contact to the open position laterally along said passage, means operative in response to movement of said cooperating contact to the open position for positively moving a quantity of arc extinguishing liquid into said arc passage and through said arc in a direction opposite to that of arc movement, vent means adjacent said stationary contact for the escape of gas and are extinguishing liquid from said are passage and additional means operative in response to predetermined pressure conditions within said are passage for controlling the escape of gas and arc extinguishing liquid from. said passage.

9. In a circuit interrupter, a body of arc extinguishing liquid, an arc extinguishing structure adapted to be immersed therein, said are extinguishing structure comprising a plurality of plates of insulating material disposed in contiguous relation, a plurality of said plates having slots therein to form a substantially com.- pletely enclosed arc passage, a pair of separable contacts within said passage for establishing an are therein, an arc horn adjacent at least one end lit of said are passage, a. plurality of slotted plates of magnetic material embedded in certain of said plates of insulating material for moving the are along said passage with one end thereof in contact with said are horn, and means operative in response to the opening movement of one of said contacts for positively directing a stream of arc extinguishing liquid along said arc horn through said are in a direction opposite to that of arc movement, at least one of said plates of insulating material adjacent said are horn having an open-end slot adjacent said contacts for causing arc extinguishing liquid and gas escaping from the passage to pass through the arc stream.

10. In a circuit interrupter, a body of are extinguishing liquid, means of insulating material immersed in said liquid defining a narrow arc chamber and a cylindrical passage communicating with said are chamber at one side thereof, a piston movable in said passage, a stationary contact extending into said are chamber adjacent the opposite side thereof, a cooperating contact movable to establish an are within said are chamber, means for moving said are within said chamber, and an actuating mechanism for operating said movable contact to establish the arc and for operating said piston to move a quantity of liquid out of said passage into said chamber in a direction opposite to that of arc movement.

11. In a circuit interrupter, a body of are extinguishing liquid, means of insulating material immersed in said liquid defining a narrow arc chamber and a passage communicating with said are chamber at one side thereof, a piston movable in said passage, a stationary contact extending into said are chamber adjacent the opposite side thereof, a cooperating contact movable to establish an are within said arc chamber, means for moving said arc within said chamber, an actuating mechanism for operating said movable contact to establish the arc and for operating said piston to move a quantity of liquid out of said passage into said chamber in a direction opposite to that of arc movement, and vent means adjacent said stationary contact to cause gas generated by the action of said are upon said liquid to flow through the arc stream in escaping from the arc chamber.

12. In a circuit interrupter, a body of are extinguishing liquid, means of insulating material immersed in said liquid defining a narrow arc chamber and a passage communicating with said are chamber at one side thereof, a piston movable in said passage, a stationary contact extending into said are chamber adjacent the opposite side thereof, a cooperating contact movable to establish an arc within said are chamber, means for moving said are within said chamber, an actuating mechanism for operating said movable contact to establish the arc and for operating said piston to move a quantity of liquid out of said passage into said chamber in a direction opposite to that of arc movement, said actuating mechanism including a linkage for balancing the reactive forces exerted upon said movable contact and said piston due to the pressure created by said are within said chamber.

13. In a circuit interrupter, a body of arc extinguishing liquid, means of insulating material immersed in said liquid defining an arc passage and a cylindrical passage adjacent thereto, said means of insulating material having an opening leading from said arc passage to said cylindrical passage adjacent at least one end thereof, a piston movable in said cylindrical passage, a pair of contacts oneof which is movable to establish an arc within said are passage, means for moving the arc along said are passage toward said opening, and an actuating mechanism for said movable contact and said piston, said actuating mechanism comprising a linkage normally maintaining said piston in liquid discharging position when said movable contact is in the closed position, said linkage operating said piston to discharge liquid from said cylindrical passage into said arc passage through said opening when said movable contact is actuated to the open position.

14. A circuit interrupter comprising a casing containing arc extinguishing liquid, a pair of arc extinguishing units immersed in said liquid, each of said units including an arc passage, a pair of separable contacts to establish an arc in said passage, a second passage communicating with said are passage, 2, piston movable in said second passage to positively inject arc extinguishing liquid into said arc passage, a movable contact carrying member for one of said contacts of said pair of contacts, and a connecting rod for said piston, means supporting said arc extinguishing units in opposed spaced relation, means directly coupling said contact carrying member of each unit with said connecting rod of a respective other unit, an actuating mechanism disposed be-' tween said are extinguishing units for simultaneously operating said contact carrying members to establish an arc in each arc extinguishing unit, and for simultaneously operating said connecting rods to cause said pistons to inject arc extinguishing liquid into the arc stream within said are extinguishing units.

15. A circuit interrupter comprising a casing containing a c extinguishing liquid, a pair of arc extinguishing units disposed in opposed spaced relation and immersed in said liquid, each of said units having an arc chamber, means for establishing an arc in each chamber including a contact rod for each unit slidable through the respective adjacent ends thereof, each of said units having a cylindrical passage communicating with its arc chamber, a piston movable in each cylindrical passage and having a connecting rod secured thereto and slidable through said respective adjacent ends of said units, a contact rod of one unit being axially aligned with the connecting rod of the other unit and coupled thereto for movement therewith, and an actuating mechanism for simultaneously moving said contact rods to establish an are within each arc chamber, said pistons being simultaneously actuated in response to said movement of said contact rods to inject a quantity of arc extinguishing liquid into each arc chamber to aid in the extinction of said arc.

16. A circuit interrupter comprising a casing containing arc-extinguishing liquid, a pair of arcextinguishing units disposed in opposed spaced relation and immersed in said liquid, each of said units having an arc chamber, a pair of contacts Within said chamber, one of which is movable for establishing an arc, a cylindrical chamber communicating with said are chamber and a piston movable within said cylindrical chamber to force additional arc-extinguishing liquid into said arc chamber, means directly connecting the piston of one unit to the movable contact of the other unit and the movable contact of the said one unit to the piston of said other unit, and actuating means for simultaneously operating said pistons and movable contacts, said actuating mechanism including a linkage for balancing the reactive forces exerted upon said movable contacts and said pistons due to the pressure created within the respective arc chambers,

1'7. In a circuit interrupter, a body of arc-extinguishing liquid, means of insulating material immersed in said liquid defining a narrow substantially enclosed arc chamber, means for establishing an are within said are chamber, an arc terminal member adjacent at least one end of said arc chamber, means for moving the are along said arc chamber with one end thereof in contact with said are terminal member, means operative in response to the establishment of an are for positively directing a stream of arc-extinguishing liquid along said are terminal member in a direction opposite to that of arc movement, and vent means disposed adjacent said separable contacts for causing arc-extinguishing liquid and gas escaping from the arc chamber to pass through the arc stream,

18. In a circuit interrupter, a body of arc-extinguishing liquid, means of insulating material immersed in said liquid defining a substantially enclosed slot-like arc passage, separable contacts for establishing an are within said are passage, an arc horn adjacent at least one end of said are passage, magnetic means for moving the arc laterally within said passage with one end thereof in contact with said are horn, means operative in response to the opening movement of said con tacts for injecting an additional quantity of arcextinguishing liquid into said passage and directing it along said are horn in a direction opposite to that of arc movement, and means adjacent said are horn operative in response to predetermined pressure conditions within said are passage for controlling the escape of gas and arc-extinguishing liquid from said passage.

19. In a circuit interrupter, a body of arc-extinguishing liquid, means immersed in said liquid defining a substantially enclosed arc passage, means for establishing an arc within said passage, means for positively injecting an additional quantity of arc-extinguishing liquid into said are passage and through the arc stream, and means for controlling the flow of arc-extinguishing liquid into said are chamber, said last-named means being actuated by said liquid injecting means to cause arc-extinguishing liquid to flow into said are passage following actuation of the interrupter to the open circuit position.

20. In a circuit interrupter, a body of arc-extinguishing liquid, means immersed in said liquid defining a substantially enclosed arc passage, means for establishing an are within said passage, a piston for injecting an additional quantity of arc-extinguishing liquid into said are passage and 

